Humans belong to a world called Earth and Earth belongs to a system called "universe". As far as our knowledge can reach, we know that universe does really exist and it is a hollow space of heavenly bodies. many scientist have found ample evidences about the Earth's scientific creation but universe is somehow still in the term called "theories". And these theories are made by astronomers'educated analysis based on cosmological facts
In our long way of studying the origin of the universe, many scientist have came up to different conclusion. and with each explanation, a majority of these have led to intriguing and complex ideas and it seems that generations to generations inheritance for the search of knowledge about the universe's creation.
One of the known theories is made by Edwin Hubble, the Big Bang Theory. This theory states that about 15 billion years ago a tremendous explosion started the expansion of the universe. This explosion is known as the Big Bang. At the point of this event all of the matter and energy of space was contained at one point. What existed prior to this event is completely unknown and is a matter of pure speculation. This occurrence was not a conventional explosion but rather an event filling all of space with all of the particles of the embryonic universe rushing away from each other. The Big Bang actually consisted of an explosion of space within itself unlike an explosion of a bomb were fragments are thrown outward. The galaxies were not all clumped together, but rather the Big Bang lay the foundations for the universe.
Next to Big Bang, is Laplace's Nebular Hypothesis.The nebular hypothesis is the idea first put forward in general terms by Immanuel Kant in 1775, and then more specifically by LaPlace in 1796, that the solar systemformed through the progressive condensation of a gassynebula which once encircled the Sun. It was suggested that as this nebula rotated and contracted, rings of gas were cast off at various stages from which the planets subsequently condensed. Accordingly, the outer planets would have formed first, followed by Mars, the Earth,Venus, and Mercury.
There is also one alike theory of Nebular Hypothesis, the Dust Cloud theory.This theory suggests that a cloud of dust and gas condensed to form our sun and planets. In the beginning, this cloud was shaped like a gigantic ball filled with both dust and hydrogen and helium gas which resulted from exploding stars, or Nova. Over billions of years, this cloud slowly condensed and flattened from a ball shape into a disk shape. As the particles moved closer to each other, they swirled faster and faster around the center of the disk, but they didn't all swirl in the same direction. They bumped into each other and lost a little energy. As the particles lost energy, they moved closer and closer to the center which caused them to swirl faster. At a certain point in time and with the force of gravity, the particles condensed to a point leading to the formation of the stars and planets.
Infinite universe or continuous creation that is what our fourth theory tells, the Steady State theory.This theory propones the idea that the universe looks the same no matter the viewpoint and that the universe has always looked like this; essentially, the the theory states that the universe is uniform throughout both time and space. The advantage of Steady State theory over some other theories is its simple and aesthetic explainations of certain troublesome topics. For example, since the universe is unchanging throughout time, the universe needs no convoluted explanation of its beginning. In addition, to account for the decrease in density that would result from expansion, steady state theory claims new matter constantly must be created in order to maintain a constant density (and therefore a static appearance).
Modern theory, that is what our last theory is, the Multiverse theory. This theory for the universe has been a recently accepted theory that describes the continuous formation of universes through the collapse of giant stars and the formation of black holes. With each of these black holes there is a new point of singularity and a new possible universe. This puts our place in the Multiverse into a small spectrum. While the size of the earth in relation to the sun is minuscule, the size of the sun, the solar system, the galaxy, and even the universe, could pale in comparison to this proposed Multiverse. It would be a shift in thinking that may help explain our big bang theory and possibly give light to the idea of parallel universes.
Even though these theories differ in some ways, these had been great contribution to Science and especially in the field of Astronomy in knowing the existence of universe. These theories were argued, planned and concluded by great astronomers and scientist of all time, that is why it is so important to know every single detail of theory they have made. Because up till now, scientists are still searching for the exact happening of how really the universe began.
